Lionhead Area

Don’t let the beautiful weather and soft snow fool you, avalanche conditions remain dangerous. A big storm just ended that heavily loaded the weak layers near the ground. Give them a bit more time to settle and stabilize before getting onto steep slopes.

The potential for triggering Wind Slab avalanches is present across the entire advisory area today, with some substantial differences in size and likelihood. In addition, big Persistent Slab avalanches are likely in the mountains around West Yellowstone. 

Skiers in the Bridger Range yesterday triggered small Wind Slab avalanches ranging from 8-12” deep and 10-25 ft wide (observation). These were not huge slides, but are plenty large enough to push you over a cliff or into rocks, and might have enough volume to bury you in the wrong spot. Winds have been blowing hard and drifting snow at all elevations. Be most wary of big slopes and those where a small slide would have big consequences. There isn’t a ton of snow to drift, so the slabs won’t be very thick and the avalanche danger is MODERATE. 

The avalanche danger is CONSIDERABLE in the rest of the advisory area.

In Northern Gallatin and Northern Madison Ranges, there have been strong winds with enough soft snow available to drift into dangerous wind slabs. There has been a little more recent snow than in the Bridger Range, so Wind Slab avalanches are more likely and will be a bit larger. Snowfall totals were variable yesterday, with some weather stations in the Big Sky area showing up to 5” of new snow. Drifts will be larger and more dangerous in areas with more new snow. Watch out for fresh wind drifts and steer around them to avoid the bulk of today’s avalanche concerns. 

In the Lionhead, Southern Madison and Southern Gallatin Ranges, weak layers near the ground are the primary driver of the avalanche hazard. This is going to be the first sunny day after the end of a big storm that heavily loaded these layers. Don’t let the beautiful weather and soft snow lull you into complacency. There was widespread avalanching the last time this snowpack was loaded (observation). Be patient and give the snowpack a little more time to settle before getting onto steep slopes. Be careful crossing underneath steep slopes as well, as this snowpack has shown the potential for triggering slides from below (video).

In the Island Park and Cooke City Areas, winds haven’t been as extreme and the weak layers near the ground are buried deeply and unlikely to be reactive, but there is quite a bit of recent snow. There has been plenty of wind to load some slopes and with so much new snow, these drifts could be deep and dangerous. Either plan to avoid wind drifted slopes entirely or choose smaller slopes and stay on high alert for the snowpack cracking as a clue that you’ve found an unstable drift.